Various approaches have been taken in order to combine the outputs of an infrared energy source and a visible light source for use as a test source. One approach is to mount a blackbody that is an infrared energy source along side an integrating sphere that provides a visible light source and to laterally move these sources on a linear slide in order to direct the light from either path into the optical path toward a focal plane. Another approach is taken when these sources are oriented perpendicularly with respect to one another. In this instance, the outputs from these sources contact a beam combiner, which directs the resulting combined energy toward the optical path. Each of these approaches has inherent disadvantages with respect to spectral fidelity, ease of use, and resulting cost.
In view of the foregoing, it has become desirable to develop a test source that combines the outputs of an infrared energy source and a visible light source to produce a fused, uniform output of energy in the visible and infrared spectra while providing independent control of the visible and infrared energy levels.